Renal cysts occur in a variety of conditions, and are the most common genetic cause of end-stage renal disease (ESRD). Despite being a major clinical concern and many of the genes causing cystic disease have been identified, knowledge of the molecular nature of the mutations has not been able to clarify the mechanism underlying cyst formation.
Renal cysts may result due to genetic disorders, non-genetic developmental disorders, and non-genetic acquired disorders. Autosomal dominant polycystic kidney disease (ADPKD) is the most common kidney cyst disease, and is among the most common inherited human diseases. With intrarenal cystogenesis as its primary characteristic, its prevalence is 1 in 400 to 1 in 1,000. Of affected families, 85% have mutations in PKD1 (located on the short arm of chromosome 16), which encodes Polycystin 1, while the rest have mutations in PKD2 (located on the long arm of chromosome 4), which encodes Polycystin 2. Individuals with PKD2 mutations generally present later and have a slower rate of progression to ESRD than individuals with PKD1 mutations. Cysts in ADPKD can arise from any part of the nephron as outpouchings connected to the tubular lumen, which eventually disconnect. Over time, they enlarge, destroying normal parenchyma, resulting in bilateral kidney enlargement, and culminating in kidney failure.
Most patients present between 20-40 years of age, although early onset (under 15 years of age) and very early onset (less than 2 years of age, even in utero) ADPKD does occur. Common renal symptoms include abdominal pain, polyuria, urinary tract infections, hematuria, and hypertension. Hepatic, pancreatic, ovarian, splenic, and intestinal diverticula may also occur.
At present, treatment options for cystic kidney disease comprise symptom management including pain management, blood pressure management, antibiotics to treat uterine tract infections, and diuretics to help remove excess fluid, and dialysis or kidney transplant. These options, particularly dialysis and transplant, are expensive and can negatively affect a patient's quality of life.